That speed controller will most likely NOT work with a buffer, especially not a Baldor.
I ran into the same issue several years ago, where I wanted to slow down buffers and belt sanders. I called several companies that specialize in custom made motor controllers, they all stated that trying to electronically control the speed on single phase motors, would quickly burn the motors up.
I finally solved the issue by going with 3 phase motors and adding a Variable Frequency Drive (VFD). Now I can go as slow as 1 RPM or as fast as the motor is rated with no loss of HP, and no fear of burning up the expensive motors. Three belt sanders and two buffers in the shop, now all with VFDs and 3 phase Baldor motors. Dont know how I ever lived without it.
